Tree Roots After Stump Grinding | Tree Masters Herts

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Stump grinding removes the stump. It does not remove the root system, and understanding what stays behind saves a certain amount of disappointment later.

What Is Actually Left

The teeth reach the stump itself and the root flare immediately around it — typically to whatever depth was agreed and perhaps half a metre or so out. Beyond that, the lateral roots remain, running outward through the soil, often considerably further than the crown of the tree ever spread.

They are cut off from anything that can feed them, so they are dead from the moment the tree came down. What happens next is decay, not growth.

The cutting wheel of a stump grinder in the grindings.

How Long Decay Takes

Fine roots — a year or two. These disappear quickly
Medium roots — three to five years
Major structural roots on a large tree — five to ten years, occasionally longer on durable timber such as oak

Warm damp soil speeds it up; heavy cold clay slows it down. Which is why the same species on the same timescale behaves differently in two Hertfordshire gardens a mile apart.

When It Does Not Matter

Most of the time. Under a lawn, a border or an area that is simply garden, decaying roots are not a problem — they break down into the soil and actually improve its structure as they go.

When It Does

Building anything. Patios, shed bases, driveways, extensions. As the roots decay the ground above them loses support and settles unevenly. This is the main reason to excavate rather than grind
Planting a replacement tree in the same spot. A new tree has to put roots into ground full of decaying wood, competing fungi and depleted nitrogen. It can be done with a large enough soil exchange, but planting a metre or two to one side is far more likely to work
Where roots are already causing damage. Lifted paving, a cracked wall, a root in a drain — grinding the stump does nothing about any of these, because the root that is doing it is metres away

Suckering, Which Is the One Surprise

Some species send up shoots from the remaining roots after the tree has gone. Poplar and lime are the worst, then cherry, elm and false acacia. Shoots can appear metres from where the tree stood, sometimes for two or three years. Repeated mowing or cutting exhausts them, but it takes persistence rather than one visit.

This is worth knowing before removing one of those species, because it is a genuine ongoing task rather than a one-off job, and nobody likes finding out afterwards.

Honey Fungus, Since It Gets Asked

Decaying roots are colonised by fungi, which is simply how decay works and is not in itself a concern. Honey fungus is the one that matters, because it is capable of attacking living plants as well as dead wood, and a large root system left in the ground can sustain it.

Where honey fungus has actually been identified — rather than assumed — removing as much root material as possible is worth doing, and that means excavation rather than grinding.

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